again........using the FCP 12.0 after upgrading from an older version. In the older version after creating Basic Latin and the proper diacritics I would easily create my European accents by right clicking on an empty glyph and choosing "create composites". This was a huge time saver and many times would require little to no adjustments.

The 12.0 version works similarly but many glyphs end up empty for no apparent reason. Why is this happening when the previous version created composites of every glyph selected?

The new version requires combining diacritical marks. If you're using an old font project with only modifier accents, add the combining diacritic equivalents, and try again.

Where the new version uses glyph names, they must be correct. Use Tools, Glyph Names, Generate to ensure that your glyphs are correctly named. Then, for example, your circumflex accent will be renamed to circumflexmod, and Jcircumflex will be generated correctly.

The full definition for Jcircumflex is as follows (I have added notes to explain):

<Composite><!-- J Circumflex -->
<GlyphMapping>308</GlyphMapping>
<Member id="1">
<GlyphMapping>74</GlyphMapping> ; Capital J
<UseMetrics>TRUE</UseMetrics> ; Use the advance width and side-bearings of Capital J
</Member>
<Member id="2">
<GlyphName>circumflexcomb.narrow</GlyphName> ; If it exists, use the narrow version of combining circumflex
<GlyphName>circumflexcomb.case</GlyphName>; If not, if it exists, use the case-sensitive combining circumflex
<GlyphName>circumflexcomb</GlyphName>; If neither, if it exists, use the combining circumflex accent
<GlyphName>circumflexmod</GlyphName> ; If none of the above, if it exists, use the modifier circumflex accent
<Pos>Auto</Pos> ; Position the accent over the Capital J
</Member>
</Composite>

Renaming the glyphs using your advice seemed to improve the situation. Now there are only a few glyphs that don't generate which I can live with. Thanks again.

Tell us which glyphs don't generate, then we can tell you which accents or base glyphs are missing or incorrectly named.

There doesn't seem to be a pattern or discernible explanation as to why certain glyphs are excluded. It's really just a random mixture. Most uppercase letters with grave or acute don't show up but lowercase is fine. In fact, almost all lowercase letters work. I'll try starting a new file as the one I'm working with is from legacy version.

So this issued has been addressed and solved on my end. I noticed that when starting a new file I'd see blank diacritics that didn't populate in the older version of your software. As suggested, I added these in.

The fastest way to add anchor based features to your font, is to automatically generate anchors and the use them to automatically generate the OpenType layout features. Your font needs combining marks. If your font misses them, you can add them by running the Eastern Europe transform script. If your font lacks anchors, just select all glyphs and select Complete Composites -> Anchor Based Reposition to add and position anchors for several Latin based characters.